The present invention relates to a front disk brake for a bicycle, and more particularly to a high performance front disk brake which can quickly and positively be installed, and driven to stop the brake disk positively stably.
A bicycle is not only a simple personal transportation vehicle but also an implement for sports. A bicycle generally has a front brake for operation by hand through a brake lever to stop the wheels from movement. A conventional bicycle front brake is a caliper brake having two brake calipers holding a respective brake pad. When the brake cable is pulled up, the brake calipers are driven to press the respective brake pads on the rim of the front wheel of the bicycle, causing the front wheel to be stopped from movement. Recently, various front disk brakes which are commonly used in motorcycles have been used in bicycles. A front disk brake is generally comprised of a brake disk fixedly fastened to the hub at the front fork of the bicycle, and a brake caliper mounted on lugs at the front fork and driven by a brake line to stop the brake disk from rotation. Because the brake caliper is driven by a brake line but not a hydraulic system as used in a motorcycle, pressure may not be evenly employed to two opposite side walls of the brake disk when the brake caliper is driven by the brake line to stop the brake disk from movement. Furthermore, because the body of the brake caliper has a narrow slot for receiving the brake disk, the brake caliper must be mounted on the lugs at the front fork of the bicycle in the accurate position so that the brake disk can be accurately suspended in the middle of the narrow slot at the body of the brake caliper. During installation, packing members may be required to adjust the position of the body of the brake caliper so that the body of the brake caliper can be accurately matched with the brake disk. This installation procedure is complicated.
According to one aspect of the present invention, the front disk brake comprises a brake disk fixedly mounted on a hub at the front fork of a bicycle, and a brake caliper mounted on lugs at the front fork of the bicycle and pulled by a brake line to stop the brake disk, wherein the brake caliper comprises a body, the body having a narrow slot, which receives the brake disk, two inside annular grooves at two opposite sides of the slot, and two sets of steel balls moved in the slot, two cam shafts mounted in the body, the cam shafts each having a head and ball grooves equiangularly spaced at the head, the ball grooves receiving the steel balls and each having a depth gradually deeper from one end toward the other end, and a pull bar driven by the brake line to turn the cam shafts, enabling the cam shafts to be respectively forced outwards by the steel balls toward two opposite side walls of the brake disk. Because the cam shafts are synchronously turned by the pull bar and forced outwards by a respective set of steel balls, pressure is evenly employed from the brake caliper to the two opposite side walls of the brake disk when the brake line is pulled up. According to another aspect of the present invention, a mounting frame is provided and installed in the lugs at the front fork of the bicycle to hold the body of the brake caliper, enabling the body of the brake caliper to be conveniently adjusted to the accurate position to match with the brake disk.